Helically fabricated electrically conductive flexible hose of the type commonly used for vacuum cleaners has been known to include a pair of conductor wires surrounded by a plastic sheath and with this composite element itself enclosed within an outer wall of overlapping turns of helically wrapped plastic strip, U.S. Pat. No. 4,167,645 and British Pat. No. 1,310,737 are examples of such constructions. In none of these electrically conductive hoses, however, is the sheathed pair of conductors applied about the outside of the helically wrapped strips which form the hose wall.
In other hose structure which do not conduct electricity and where one or more wires are used only for reinforcing purposes, it has been known to apply a sheathed wire about an innermost helically wrapped plastic strip, as for example in U.S. Pat. No. 4,304,266, but here too the sheathed wire is enclosed within an outer wall ply and does not form the outermost element of the structure. Longitudinal and circumferential reinforcing cords may be incorporated in these hose wall structures as taught in U.S. Pat. No. 4,224,463.
It is the principal purpose of the present invention to provide the most economical wire reinforced electrically conductive hose structure. This is achieved by forming a simple inner hose wall of overlapping convolutions of plastic strip, whether of single or multiple ply or reinforced with cords, and then helically applying a pair of sheathed wires about such a wall to form the outermost element of the structure.